1. Field of the Invention
The present invention is related to hepatitis vaccines. More particularly, the present invention is related to producing live or killed virus vaccines employing full-length, hepatitis-A virus cDNA or RNA transcribed therefrom as the transfecting agent. The cDNA can be specifically mutated to produce a hepatitis-A virus with the desired vaccine characteristics.
2. State of the Art
Heretofore live vaccines have been produced by the conventional method of producing attenuated virus by passaging wild type virus in cell culture. This is an empirical process which depends on random natural mutation. Randomness of the mutational process makes it difficult to predict and obtain viruses which are infectious yet sufficiently attenuated so as to be suitable as a vaccine (J. Med. Virol. 20:165-175, 1986). The present invention overcomes such limitations of the conventional methodology and provides a new approach to vaccine preparation.